[U-Boot] [PATCH v2] DW SPI: Get clock value from Device Tree

[Marek Vasut]

On 10/30/2017 07:04 AM, Jagan Teki wrote:
> On Sat, Oct 28, 2017 at 5:09 PM, Marek Vasut <marex at denx.de> wrote:
>> On 10/27/2017 03:54 PM, Eugeniy Paltsev wrote:
>>> On Tue, 2017-10-24 at 15:22 +0530, Jagan Teki wrote:
>>>> On Tue, Oct 24, 2017 at 11:38 AM, Marek Vasut <marex at denx.de> wrote:
>>>>> On 10/23/2017 01:43 PM, Eugeniy Paltsev wrote:
>>>>>> On Thu, 2017-10-19 at 13:20 -0500, Dinh Nguyen wrote:
>>>>>>>
>>>>>>> On 10/19/2017 10:51 AM, Marek Vasut wrote:
>>>>>>>> On 10/19/2017 05:36 PM, Eugeniy Paltsev wrote:
>>>>>>>>> On Tue, 2017-10-17 at 20:32 +0530, Jagan Teki wrote:
>>>>>>>>>> On Tue, Oct 17, 2017 at 8:27 PM, Alexey Brodkin
>>>>>>>>>> <Alexey.Brodkin at synopsys.com> wrote:
>>>>>>>>>>> Hi Jagan,
>>>>>>>>>>>
>>>>>>>>>>>> -----Original Message-----
>>>>>>>>>>>> From: Eugeniy Paltsev [mailto:paltsev at synopsys.com]
>>>>>>>>>>>> Sent: Tuesday, October 17, 2017 4:33 PM
>>>>>>>>>>>> To: jagannadh.teki at gmail.com
>>>>>>>>>>>> Cc: u-boot at lists.denx.de; uboot-snps-arc at synopsys.com
>>>>>>>>>>>> Subject: [uboot-snps-arc] Re: [PATCH v2] DW SPI: Get clock value from Device Tree
>>>>>>>>>>>>>
>>>>>>>>>>>>> How hard it is to make others to use clock manager? do you have any list?
>>>>>>>>>>>>
>>>>>>>>>>>> clock_manager.h is an old (and non-generic) way to deal with different clocks.
>>>>>>>>>>>> For example in SOCFPGA_GEN5 and SOCFPGA_ARRIA10 clock_manager.h provides
>>>>>>>>>>>> cm_get_spi_controller_clk_hz function to deal with spi controller clock.
>>>>>>>>>>>>
>>>>>>>>>>>> But today we have another, linux-like alternative: to bind clocks via device tree
>>>>>>>>>>>> and manipulate with clocks via generic functions provided by clk.h
>>>>>>>>>>>>
>>>>>>>>>>>> In this patch I added option to get clock via device tree using standard bindings
>>>>>>>>>>>> and restrict clock_manager.h functions usage only to targets which still use it,
>>>>>>>>>>>> so new targets can simply bind clock via device tree and they do not need to
>>>>>>>>>>>> implement/define something in clock_manager.h
>>>>>>>>>>>>
>>>>>>>>>>>> So we don't need to make others to use clock manager :)
>>>>>>>>>>>
>>>>>>>>>>> Maybe it worth trying the other way around and think about switching SOCFPGA platforms to
>>>>>>>>>>> generic clk framework?
>>>>>>>>>>
>>>>>>>>>> Yes, ie what exactly I thought of, thanks!
>>>>>>>>>
>>>>>>>>> I checked cm_get_spi_controller_clk_hz implementation in SOCFPGA_GEN5 and
>>>>>>>>> SOCFPGA_ARRIA10: we can't simply replace it with "fixed-clock" driver as it
>>>>>>>>> manipulate with real hardware.
>>>>>>>>> The only way to do it is to replace SOCFPGA* clock manager functions by real
>>>>>>>>> clock driver.
>>>>>>>>>
>>>>>>>>> And given I don't have mentioned hardware so I barely can help with
>>>>>>>>> those improvements on SOCFPGA. That said if there're no short-term plans to
>>>>>>>>> switch SOCFPGA to clk framework maybe we'll be OK with my workaround with #ifdefs?
>>>>>>>>
>>>>>>>> Wait for Dinh's reply ...
>>>>>>>>
>>>>>>>
>>>>>>> Honestly, I don't have too much time to work on this right now. So I
>>>>>>> really don't when it can get done. But it'll go on my to-do list.
>>>>>>>
>>>>>>> Dinh
>>>>>>
>>>>>> Yep, thanks for your comments.
>>>>>>
>>>>>> So, Jagan,
>>>>>> given Dinh's reply, could you please apply this patch?
>>>>>
>>>>> I'd really hate it to start seeing soc-specific ifdefs in drivers,
>>>>> that's IMO not acceptable. A __weak override might be a temporary
>>>>> solution I'd be willing to live with though.
>>>>
>>>> I would rather like to see some check on clock manager itself whether
>>>> CONFIG_IS_ENABLED(CLK) is using or not? this can tends not to use
>>>> __weak as well soc #ifdefs in driver.
>>>>
>>>
>>> Actually I don't understand what do you mean.
>>> Even if I add any #ifdefs to the clock_manager.h I still need to wrap clock_manager.h
>>> include with #ifdefs as clock_manager.h is defined only for two
>>> targets - SOCFPGA_GEN5 and SOCFPGA_ARRIA10.
>>>
>>> #if defined(CONFIG_TARGET_SOCFPGA_GEN5) || defined(CONFIG_TARGET_SOCFPGA_ARRIA10)
>>> #include <asm/arch/clock_manager.h>
>>> #endif
>>>
>>> And I think it is better to add this #ifdef in driver than create empty
>>> clock_manager.h file for every new target which uses this driver.
> 
> Check CLK in clock-manager like below, of-course cm_get_l4_noc_hz used
> in other IP's as well. we need to carefully adding these check and if
> require add CLK for remaining drivers as well. the reason for adding
> checks in clock-manager is it may be removable code if all use CLK.

I do not understand what you're trying to tell me, but the patch below
makes no sense. What I would like to see is a weak function in the
driver and that function be overriden in the socfpga clock manager.

> --- a/arch/arm/mach-socfpga/clock_manager_arria10.c
> +++ b/arch/arm/mach-socfpga/clock_manager_arria10.c
> @@ -1066,10 +1066,17 @@ unsigned int cm_get_mmc_controller_clk_hz(void)
>         return clk_hz / 4;
>  }
> 
> +#if CONFIG_IS_ENABLED(OF_CONTROL) && CONFIG_IS_ENABLED(CLK)
> +unsigned int cm_get_spi_controller_clk_hz(void)
> +{
> +       return 0;
> +}
> +#else
>  unsigned int cm_get_spi_controller_clk_hz(void)
>  {
>         return cm_get_l4_noc_hz(CLKMGR_MAINPLL_NOCDIV_L4MPCLK_LSB);
>  }
> +#endif
> 
> thanks!
> 


-- 
Best regards,
Marek Vasut